Signalling compounds and methods for detecting hydrogen peroxide

ABSTRACT

Methods and compound useful for detecting a source of hydrogen peroxide are disclosed wherein a signalling compound of the formula: 
                         
is reacted with peroxide. Sig is a non-polymeric organic group, B is a boron atom, and each R is independently selected from hydrogen, alkyl and aryl groups and can be joined together as a straight or branched alkylene chain forming a ring or as an aromatic ring. A detectable product compound of the formula Sig—OH or Sig—O −  is produced and detected by measuring color, absorbance, fluorescence, chemiluminescence, or bioluminescence. The signalling compound itself does not possess the detectable property or does so only to a very weak degree. The methods can be used as a detectable signal in assays for peroxide or peroxide-producing enzymes and in assays employing enzyme-labeled specific binding pairs.

FIELD OF THE INVENTION

The present invention relates to methods and compounds for detectinghydrogen peroxide. In particular, the present invention relates tosignalling compounds which react with hydrogen peroxide to produce adetectable species. The invention further relates to assay methods fordetecting hydrogen peroxide and for detecting peroxide-generatingsystems.

BACKGROUND OF THE INVENTION

1. Detection of Peroxide. Various methods are known for detectinghydrogen peroxide and related peroxides.

a. Colorimetric Detection of Peroxide. Compounds which react withhydrogen peroxide and a peroxidase to produce a colored product includeABTS, 4-aminoantipyrine (Anal. Letters, 26, 87 (1993)), and leuco dyessuch as Leucocrystal Violet. Numerous methods exist for detectinghydrogen peroxide using a chromogen and a transition metal compound.

b. Fluorescent Detection of Peroxide. Compounds which react withhydrogen peroxide and a peroxidase to produce a fluorescent productinclude 2′,7′-dichlorofluorescin, dihydrorhodamine 123 (Arch. Biochem.Biophys., 302(2), 348-55 (1993)) and N-acetylresorufin, (Chemical &Pharmaceutical Bulletin, 49(3), 294-29, (2001)).

c. Chemiluminescent Detection of Peroxide. Acridinium esters andsulfonamides undergo a rapid oxidation reaction with hydrogen peroxideat alkaline pH to produce a flash of chemiluminescence (e.g. U.S. Pat.Nos. 4,745,181, 4,946,958, 5,281,712 and 5,468,646). Lucigenin(9,9′-biacridinium dinitrate) is oxidized by hydrogen peroxide toproduce chemiluminescence (Maskiewicz, et al., J. Am. Chem. Soc., 101,5347-5354 (1979)).

Esters and amides of oxalic acid react with hydrogen peroxide in thepresence of a fluorescer to produce chemiluminescence. This reactionformed the basis of the well-known “light stick” technology used innovelty items.

Cyclic acylhydrazides including the amine-substituted compounds luminoland isoluminol, hydroxy-substituted compounds and heterocyclic analogsreact with hydrogen peroxide and a metal catalyst to producechemiluminescence. Metal catalysts include heme, hexacyanoferrate andother transition metal ions including Cu(II) and Co(II).

U.S. Pat. No. 5,545,834 describes the chemiluminescent reaction ofspiro-acridan compounds with hydrogen peroxide. The reaction is enhancedby the addition of horseradish peroxidase.

d. Enzymatic Detection of Peroxide. Various reagents have been developedfor detection of peroxidase activity by reaction of a peroxidase enzyme,a source of hydrogen peroxide and an indicating reagent. These reagentstherefore also serve to detect hydrogen peroxide. Color, fluorescence orchemiluminescence can be produced with use of the appropriate reagent.Chemiluminescent substrates include amino-substituted cyclicacylhydrazides such as the well-known luminol and isoluminol (Anal.Chim. Acta, 170, 101-107, (1985)), heterocyclic acylhydrazides (M. Ii,et al., Biochem. Biophys. Res. Comm., 193(2), 540-5 (1993); U.S. Pat.No. 5,324,835 and Y. Tominaga, et al., Tetrahedron Lett., 36, 8641-4(1995)), and hydroxy-substituted phthalhydrazides (U.S. Pat. No.5,552,298).

Applicant's U.S. Pat. Nos. 5,491,072, 5,523,212 and 5,593,845 disclosechemiluminescent N-alkylacridan-carboxylic acid derivatives whichproduce light upon reaction with a peroxide and a peroxidase.Applicant's U.S. Pat. No. 5,922,558 discloses a class of compoundscontaining an electron-rich double bond as chemiluminescent peroxidasesubstrates.

European Patent Specification EP0682254B1 discloses assay methods inwhich a conjugate of an enzyme that generates hydrogen peroxide is usedand the peroxide is detected by acridinium ester chemiluminescence.

Fluorescent substrates for peroxidase include3-(4-hydroxyphenyl)propionic acid as disclosed in U.S. Pat. No.6,040,150,2-(4-hydroxyphenyl)acetic acid disclosed in Zaitsu and Ohkura,Anal. Biochem., 109, 109-113 (1980), homovanillic acid and tyramine (Y.Li, et al., Anal. Chim. Acta, (340), 159-168, (1997)),o-phenylenediamine and N,N′-dicyanomethyl-o-phenylenediamine (Li, etal., Microchem. J., 53(4), 428-436 (1996)), amide and carbamatederivatives of p-aminophenol (M. Kawaguchi, et al., Bioluminescence andChemiluminescence Perspectives for the 21st Century, A. Roda et al.,Eds., Wiley & Sons, Chichester, pp 508-511, (1999)),3,4-dihydro-2(1H)-quinoxalone and related derivatives (Li, et al., Anal.Chim. Acta, 340(1-3), 159-168 (1997)), reduced forms of fluorescein,rhodamine and other xanthine dyes and fluorinated derivatives of thelatter (U.S. Pat. No. 6,162,931).

Chromogenic or color-forming substrates for peroxidase includetetramethylbenzidine, chlorophenol red and2,2′-Azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (Ngo, T. T. InImmunochemistry of Solid-Phase Immunoassay, Butler, J. E. Ed., CRC: BocaRaton, 1991, pp 85-102.).

2. Fluorescent and Colored Boronic Acid Sensors. Fluorescent and coloredcompounds containing boronic acid substituents for use in detectionmethods are disclosed in U.S. Pat. Nos. 4,496,722, and 4,659,817. Theboronic acid group complexing compounds coordinate to and bind pairs ofhydroxy, amine or thiol groups to form a fluorescent or colored complex.The binding partner can be either a carrier compound such as a buffersalt or it can be a biological substance which is to be tagged.Representative of the latter are cellular components. These methodsdiffer fundamentally from the methods of the present invention by virtueof the unbound boronic acid compound being already colored orfluorescent to the same extent as the bound complex with the carrier orcellular component. Color or fluorescence is not created during theconduct of the methods.

The '772 and '817 patents also disclose peroxide assays in which theboronic acid substituted fluorescent or colored compounds are reactedwith hydrogen peroxide to cleave the fluorescent or colored reportermoiety from the boronic acid group. Detection requires a separation stepin order to measure the liberated reporter. Organic solvent extraction,release from a solid phase and filtration are disclosed as means toseparate the released reporter from the reporter-boronic acid compound.Again, in contrast to the methods of the present invention, color orfluorescence is not created during the conduct of the methods.

Colored or fluorescent boronic acid complexing agents for use indetection of glycated blood proteins such as hemoglobin are disclosed inU.S. Pat. Nos. 5,242,842, 5,506,144 and 5,739,318. The boronic acidgroups coordinate to and bind pairs of hydroxy groups to form a coloredor fluorescent complex. The complex is separated from unbound complexingagent and measured. Detection does not involve any peroxide. This modeof measurement differs from the present invention in requiring aseparation and that the unbound boronic acid compound is already coloredor fluorescent to the same extent as the bound protein complex.

PCT Publication WO 02/46752 discloses assays for polyhydroxyl compounds,e.g. glucose, using boronic acid-quencher conjugates which bind to andquench the fluorescence of appropriately substituted fluorescers.Binding of the fluorescer via the boronic acid group of the quencher isreversed in the presence of the polyhydroxyl compound which competes forbinding with the boronic acid group.

3. Phenylboronic acid Peroxidase Enhancers. U.S. Pat. Nos. 5,512,451 and5,629,168 disclose phenylboronic acid compounds as enhancers of theperoxidase-catalyzed chemiluminescent oxidation of luminol with hydrogenperoxide. In the methods disclosed therein the boronic acid compoundpromotes the reaction of the peroxidase in oxidizing luminol.Chemiluminescence is produced from an oxidized form of luminol and notfrom the boronic acid. Arylboronic acid derivatives are disclosed asperoxidase enhancers in the chemiluminescent oxidations of acridancompounds in U.S. Pat. Nos. 5,723,295 and 5,922,558.

None of the foregoing methods disclose the use of boronic acid orboronate ester signalling compounds in a method for detecting and, whendesired, quantifying the amount of hydrogen peroxide wherein theperoxide causes the formation of a detectable signal from the precursorsignalling compound which does not itself possess the property beingdetected.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide boronic acid orboronate ester signalling compounds which react with a source ofhydrogen peroxide to produce a detectable product having a detectableproperty, which compounds do not possess the property being detected.

It is an object of the present invention to provide compounds whichreact with a source of hydrogen peroxide to produce a colored,fluorescent, chemiluminescent or bioluminescent product.

It is a further object of the present invention to provide methods fordetecting a source of hydrogen peroxide employing the present compounds.

It is a further object of the present invention to provide methods forquantifying the amount of hydrogen peroxide by use of the abovesignalling compounds.

It is a further object of the present invention to provide methods fordetecting enzymes which generate hydrogen peroxide by reaction of theenzyme with a substrate for the enzyme and detecting the hydrogenperoxide so generated by use of the above signalling compounds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph relating the amount of hydrogen peroxide to thechemiluminescence intensity at 15 min emitted by 100 μL of a reagentdescribed in Example 10. The term S-B refers to the chemiluminescencesignal (S) in Relative Light Units (RLU) in the presence of hydrogenperoxide corrected for background chemiluminescence (B) in the absenceof hydrogen peroxide.

FIG. 2 is a graph relating the amount of glucose oxidase to fluorescenceintensity according to Example 16. Samples containing various amounts ofglucose oxidase were incubated with 0.1 M glucose for 30 min. The H₂O₂produced was assayed with a reagent containing the signalling compound2-naphthylboronic acid to produce the fluorescent compound 2-naphthol.

FIG. 3 is a graph relating the amount of glucose to fluorescence asdescribed in Example 17. Samples containing various amounts of glucosewere incubated at room temperature with glucose oxidase and thesignalling compound 2-naphthylboronic acid. Fluorescence was measuredafter 30 min.

FIG. 4 is a graph depicting the fluorescence spectra of abis(benzothiazolyl)boronate ester signalling compound before (A) andafter (B) reaction with urea peroxide.

FIG. 5 is a graph depicting the grow in of fluorescence at 440 nm fromthe reaction of 4-methylcoumarin-7-boronic acid pinacol ester in 0.3 Mtris buffer, pH 9.3 with 3 mM urea peroxide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definitions:

Alkyl—A branched, straight chain or cyclic hydrocarbon group containingfrom 1-20 carbons which can be substituted with 1 or more substituentsother than H. Lower alkyl as used herein refers to those alkyl groupscontaining up to 8 carbons.

Alkenyl—A branched, straight chain or cyclic hydrocarbon groupcontaining at least one C—C double bond and containing from 2-20carbons. Lower alkenyl as used herein refers to those alkenyl groupscontaining up to 8 carbons.

Alkynyl—A branched or straight chain hydrocarbon group containing atleast one C—C triple bond and containing from 2-20 carbons. Loweralkynyl as used herein refers to those alkynyl groups containing up to 8carbons.

Analyte—A substance the presence or amount of which is to be measured ina sample by an assay. Analytes include organic and biological moleculesto which a specific binding partner having a specific binding affinityexists. Exemplary analytes include, without limitation, single strandedor double stranded DNA, RNA, DNA-RNA complexes, oligonucleotides,antibodies, antibody fragments, antibody-DNA chimeras, antigens,haptens, proteins, lectins, avidin, streptavidin and biotin. Otherexemplary analytes also include hydrolytic enzymes, inhibitors ofhydrolytic enzymes and dihydroxyaromatic compounds.

Aryl—An aromatic ring-containing group containing 1 to 5 carbocyclicaromatic rings, which can be substituted with 1 or more substituentsother than H.

Biomedical analysis—Analyses of samples of biological origin foranalytes of interest. The analyses can be immunoassays, western blots,northern blots, Southern blots, DNA hybridization assays, DNA sequenceanalysis, colony hybridizations, gene expression analysis, highthroughput drug screening, detection of infectious agents or pathogensand the like.

Detectable signal—physical property resulting from measurement of thereaction product of the present reactions. The signal can be lightproduced by a chemiluminescent or bioluminescent reaction or byfluorescence. The signal can also be formation of color or a change ofcolor or the change of absorption of ultraviolet or infrared radiation.The signal can also be a measurement of the molecular mass of theproduct or a specific signal in an NMR spectrum.

Halogen—Fluorine, chlorine, bromine or iodine atoms.

Heteroaryl or heteroaromatic—An aromatic ring-containing groupcontaining 1 to 5 carbocyclic aromatic rings in which at least one ofthe ring carbon atoms is replaced with a nitrogen, oxygen or sulfur atomand which can be substituted with 1 or more non-H substituents.

Luminescent—capable of emitting light when excited to an electronicexcited state. The light can be emitted either as fluorescence whendecaying from a singlet excited state or as phosphorescence whendecaying from a triplet excited state.

Peroxide—A compound containing an O—O bond, preferably hydrogen peroxideor a complex of hydrogen peroxide such as urea peroxide, perborate orpercarbonate.

Sample—A fluid containing or suspected of containing one or moreanalytes to be assayed. Typical samples which are analyzed by thechemiluminescent reaction method are biological samples including bodyfluids such as blood, plasma, serum, urine, semen, saliva, cell lysates,tissue extracts and the like. Other types of samples include solvents,seawater, industrial water samples, food samples and environmentalsamples such as soil or water.

Source of hydrogen peroxide—a compound which is hydrogen peroxide or itssalts such as sodium or potassium peroxide or hydrogen peroxide incomplexed form such as urea peroxide, perborate salts and percarbonatesalts.

Specific binding pair—Two substances which exhibit a mutual bindingaffinity. Examples include antigen-antibody, hapten-antibody orantibody-antibody pairs, complementary oligonucleotides orpolynucleotides, avidin-biotin, streptavidin-biotin, hormone-receptor,lectin-carbohydrate, IgG-protein A, nucleic acid-nucleic acid bindingprotein and nucleic acid-anti-nucleic acid antibody.

Substituted—Refers to the replacement of at least one hydrogen atom on agroup by a non-hydrogen group. It should be noted that in references tosubstituted groups it is intended that multiple points of substitutioncan be present unless clearly indicated otherwise.

Triflate—trifluoromethanesulfonate ester CF₃SO₃—.

The present invention concerns methods using signalling compounds whichreact with a source of hydrogen peroxide to produce a detectablecompound capable of producing a detectable signal. The signallingcompounds comprise one or more boronic acid or boronate ester groupssituated on a signalling moiety designated Sig.

In the signalling compounds each R is independently selected fromhydrogen, alkyl and aryl groups and can be joined together as a straightor branched alkylene chain forming a ring or as an aromatic ring. Thegroup Sig is not readily detectable until the boron-containing group isreplaced by a hydroxyl group through the reaction of hydrogen peroxide.Thus, reaction of the signalling compound with hydrogen peroxidereplaces the boron-containing substituent with a hydroxyl group creatingthe detectable moiety. The product Sig-OH is readily distinguished fromthe starting signalling molecule by the creation of a detectableproperty. The starting signalling molecule itself does not possess thedetectable property or does so only to a very weak degree so that theproduct is easily distinguished and quantifiable.

Although the detectable product is depicted in the protonated formhaving a hydroxy group —OH, the detectable product can and in many caseswill exist in the deprotonated form as the oxyanion or as an equilibriummixture of protonated and deprotonated form. The exact form will begoverned by factors such as reaction pH and electronic excitation whichis known to ionize groups such as phenols by increasing their acidity inan electronic excited state. Both forms are considered to be within thescope of detectable product species in all embodiments of the invention.

Furthermore the present invention concerns methods of detecting hydrogenperoxide comprising reacting the signalling compounds with a source ofhydrogen peroxide to produce a detectable product compound having adetectable property, detecting the product by measuring the detectableproperty and relating the detectable product to the hydrogen peroxide.The methods of the invention can be used in a quantitative fashion todetermine the amount of hydrogen peroxide in a sample known or suspectedto contain hydrogen peroxide. Such a method would comprise the steps ofreacting the sample known or suspected to contain hydrogen peroxide witha signalling compound to produce a detectable product compound,detecting the detectable product compound by measuring a detectableproperty, and relating the detectable product to the amount of hydrogenperoxide.

Detectable properties which can be used to detect and therebydifferentiate the product from the signalling compound reactant broadlycomprise any physical property which is altered by the reaction withperoxide and include color or absorption of light of any suitablewavelength from ultraviolet to visible to infrared, fluorescence,chemiluminescence, bioluminescence, molecular mass, and other meansdirectly influenced by molecular structure including nuclear magneticresonance frequency (NMR), especially ¹H and ¹³C NMR. Preferredproperties permit quantification of the amount of hydrogen peroxide byquantifying the amount or fraction of the detectable product which isformed and are selected from color, absorbance, fluorescence,chemiluminescence, and bioluminescence. The detectable property of theproduct compound preferably differs from that of the signalling compoundby at least a factor of ten, more preferably by at least a factor of 100and still more preferably by at least a factor of 1000. Preferreddetectable properties are selected from fluorescence, chemiluminescenceand bioluminescence. Importantly, detection of the product can beperformed in the presence of the reactant signalling compound and doesnot require a separation.

Sources of hydrogen peroxide include hydrogen peroxide and its saltssuch as sodium or potassium peroxide, and peroxide in complexed formsuch as urea peroxide, perborate salts, percarbonate salts andpercarboxylic acids and their salts. Biological sources of hydrogenperoxide are included as hydrogen peroxide is known to be produced invivo in leukocytes and certain antibodies. Sources of hydrogen peroxidealso encompasses enzymatic generation systems as discussed below.

Signalling compounds useful in the methods of the invention comprise oneor more boronic acid or boronate ester groups situated on a signallingmoiety designated Sig. The group Sig can be any organic group capable ofbeing detected as described above. Because of the near universality ofdetection of organic compounds by techniques such as NMR spectroscopyand mass spectrometry the nature of the Sig group encompassesessentially any non-polymeric organic group. Aliphatic, unsaturated,aromatic and heterocyclic groups can be used as the Sig group. Thedetectable property when using mass spectrometric detection is themolecular mass of the product which of course differs from that of thestarting signalling compound by at least 27 mass units up to about 200mass units depending on the nature of the groups R⁵ and R⁶. The groupSig is limited only by the mass resolution of the measurement and theability to detect the molecular ion. Sig groups having a molecular massup to about 2000 will be detectable.

Detection by NMR spectroscopy allows detection of any reaction productSig-OH which can be distinguished from the corresponding signallingcompound. The detection can be performed by ¹³C NMR analysis of theresonance frequency of the carbon undergoing the C—B to C—O bond change.Monitoring the change is most conveniently performed in ¹H-decoupledmode so that the signal will be a singlet peak in most cases. Thedetection can also be performed by ¹H NMR analysis of the resonancefrequency of a hydrogen atom on or near the carbon undergoing the C—B toC—O bond change. By near is meant that the hydrogen atom is substitutedon another carbon atom or other atom within 1-3 atoms of the carbonundergoing the C—B to C—O bond change. Some examples of hydrogen atomsdetectable by the present invention and useful in a qualitative orquantitative method for detecting the presence or amount of hydrogenperoxide are shown below.

Signalling compounds detectable by NMR techniques when reacted inaccordance with the present invention are preferably non-polymericorganic compounds wherein the Sig group has a molecular mass less thanabout 2000. Desirably the group Sig will not contain other atoms orgroups which are chemically similar to the particular nucleus beingdetected and thereby obscure its detection. Quantification is readilyachieved using NMR-based detection. A sample containing hydrogenperoxide is reacted with a signalling compound in an amount at leastequal to the amount of the peroxide. The entire sample or a knownfraction thereof is analyzed and the extent of conversion to thereaction product Sig-OH determined from the magnitude of the selectedcharacteristic resonance signal.

A preferred class of groups for Sig comprises substituted andunsubstituted aromatic or heteroaromatic ring groups. Signalingcompounds in this class generally possess a chromophore or fluorophorewhen converted to the product by reaction with a source of hydrogenperoxide and can therefore be used with an absorption or fluorescencedetection scheme.

One group of signalling compounds comprise those boronic acid orboronate ester compounds which, upon conversion to the phenolic productSig-OH through reaction with a source of hydrogen peroxide, becomecapable of generating chemiluminescence. Among the signalling compoundsof the present invention which are converted to chemiluminescentproducts are a novel family of 1,2-dioxetane compounds. The previouslyunknown boronic acid or boronate ester substituted dioxetanes are offormula I:

wherein A¹-A³ represent organic groups having from 1-20 carbon atoms andAr is an aromatic or heteroaromatic ring group, wherein A¹ and A² or A¹and A³ or A³ and Ar can be combined to form a ring, and each R isindependently selected from hydrogen, alkyl and aryl groups and and canbe joined together as a straight or branched alkylene chain forming aring or as an aromatic ring. All such groups A¹-A³, Ar and R can besubstituted with non-hydrogen atoms. These compounds have beenunexpectedly discovered to react with hydrogen peroxide to producechemiluminescence.

A group of preferred 1,2-dioxetane compounds for detection of hydrogenperoxide by chemiluminescence have formula II:

wherein R¹ is is an organic group having from 1-20 carbon atoms whichcan be substituted with non-hydrogen atoms and can be combined with R²or R³, R² is an aromatic or heteroaromatic ring group which can includeadditional substituents selected from halogens, alkyl, substitutedalkyl, alkoxy, substituted alkoxy, carbonyl, carboxyl, amino andalkylamino groups, R³ and R⁴ are independently selected from acyclic andcyclic organic groups containing from 3-20 carbon atoms and which can besubstituted with heteroatoms and R⁵ and R⁶ are independently selectedfrom hydrogen, alkyl and aryl groups and and can be joined together as astraight or branched alkylene chain forming a ring or as an aromaticring. In another group of compounds of formula II, R³ and R⁴ arecombined together in a cyclic or polycyclic alkyl or alkenyl group whichis spiro-fused to the dioxetane ring and contains 6 to 20 carbon atomsand which can include additional non-hydrogen substituents. A preferredpolycyclic alkyl group is a substituted or unsubstituted adamantylgroup.

A preferred group of compounds are boronic acids wherein R⁵ and R⁶ areboth hydrogen atoms. Another preferred group of compounds contain an Rgroup selected from substituted or unsubstituted phenyl and substitutedor unsubstituted naphthyl groups. In another preferred group ofcompounds R¹ is a lower alkyl group which can be substituted withnon-hydrogen atoms. In another preferred group of compounds R³ and R⁴are each branched alkyl or cycloalkyl groups having from 3-20 carbonatoms. In another preferred group of compounds R³ and R⁴ are combinedtogether as a spiro-fused polycyclic alkyl or alkenyl group and is morepreferably an adamantyl group or a substituted adamantyl group havingone or more substituent groups selected from halogens, alkyl,substituted alkyl, alkoxy, substituted alkoxy, carbonyl, carboxyl,phenyl, substituted phenyl, amino and alkylamino groups covalentlybonded thereto.

Dioxetane compounds of formula I and II are converted by reaction with asource of hydrogen peroxide to the corresponding hydroxy-substituteddioxetane which produces chemiluminescence rapidly when in thedeprotonated state.

A large number of species are known to function in the method of thepresent invention and are encompassed within the class of compoundsembodied by formula I. This knowledge is predicated in part on theknowledge that once a hydroxy-substituted dioxetane is formed byreaction of a boronic acid or boronate ester dioxetane derivative withperoxide, it will spontaneously decompose when deprotonated to producelight. Many such triggerable dioxetanes are known. Particularembodiments of compounds of formula I and II which react according tothe present invention to produce chemiluminescence comprise thoseboronic acid or boronate ester dioxetanes which are converted byhydrogen peroxide to known hydroxy-substituted dioxetanes. Theseinclude, without limitation

wherein R⁷ is a cyclic or polycyclic alkyl or alkenyl group,

wherein Y is a substituent group selected from halogens, alkyl,substituted alkyl, alkoxy, substituted alkoxy, carbonyl, carboxyl,phenyl, substituted phenyl, amino and alkylamino groups,

wherein Z is a substituent group selected from halogens, alkyl,substituted alkyl, alkoxy, substituted alkoxy, carbonyl, carboxyl,phenyl, substituted phenyl, amino and alkylamino groups,

wherein n=1 or 2, R is selected from alkyl and benzyl and R′ is selectedfrom alkyl, phenyl and substituted phenyl; T is selected from alkyl,cycloalkyl and polycycloalkyl groups any of which can be substitutedwith non-hydrogen atoms, Ak is a branched alkyl or cycloalkyl groupwhich can be substituted with non-hydrogen atoms,

wherein W is O or S;

particularly where the group R¹ is lower alkyl or halogenated alkyl suchas CH₃, CD₃, or CH₂CF₃ and Y is 4-choro or H

-   -   wherein W is O or S;        and boronate ester derivatives thereof as described above.

In addition to the foregoing structures, boronate ester analogs of thesecompounds are also useful in the practice of the present methods. Inplace of the B(OH)₂ group, the dioxetane compounds can contain a grouphaving the formula B(OR)₂ wherein R can be an alkyl, specially a loweralkyl, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,t-butyl and the like or an aryl ring group such as phenyl. The R groupscan be joined together in a ring e.g.

Another group of signalling compounds of formula I comprise dioxetanecompounds substituted with a sulfur atom on the dioxetane ring. Theseinclude, without limitation

wherein R¹, R², R³, R⁴, R⁵, and R⁶ are as described above, and R⁷ is acyclic or polycyclic alkyl or alkenyl group any of which can besubstituted with non-hydrogen atoms. Particularly, signalling compoundsof formula III comprise compounds in which R¹ is an organic group havingfrom 1-20 carbon atoms which can be combined with R² or R³, R² is anaromatic or heteroaromatic ring group which can include additionalsubstituents selected from halogens, alkyl, substituted alkyl, alkoxy,substituted alkoxy, carbonyl, carboxyl, amino and alkylamino groups, R³and R⁴ are independently selected from acyclic and cyclic organic groupscontaining from 3-20 carbon atoms and which can be substituted withheteroatoms, and R⁵ and R⁶ are independently selected from hydrogen,alkyl and aryl groups and can be joined together as a straight orbranched alkylene chain forming a ring or as an aromatic ring.

Preferred embodiments include without limitation

wherein Y is a substituent group selected from hydrogen, halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, phenyl, substituted phenyl, amino and alkylamino groups,

wherein Z is a substituent group selected from hydrogen, halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, phenyl, substituted phenyl, amino and alkylamino groups.

Another aspect of the present invention is the use of a signallingcompound including the compounds described above in a method to producechemiluminescence by reaction with hydrogen peroxide. Reaction of thecompound with hydrogen peroxide in an aqueous solution produces easilydetected chemiluminescence when the reaction is conducted at alkalinepH. The reaction can be conducted optionally in the presence of achemiluminescence enhancer.

In a preferred method of producing chemiluminescence, compound I or IIis reacted with a peroxide in an alkaline solution with a pH of at leastabout 8 to produce chemiluminescence which commences upon reaction ofthe peroxide and compound I or II according to the reaction scheme.

Reaction of the boronic acid or boronate ester-substituted dioxetanewith hydrogen peroxide is believed to form a hydroxyaryl or aryloxidesubstituted dioxetane intermediate by replacing the carbon-boron bondwith a carbon-oxygen bond. Under conditions in which of the phenolic OHgroup is at least partly ionized, decomposition of the dioxetane ensueswith emission of light. The base or alkaline pH-triggered decompositionof hydroxyaryl substituted dioxetanes is well known in the art ofchemiluminescence. Examples of such triggerable dioxetanes with variousstructural modifications are described in for example, U.S. Pat. Nos.5,886,238, 6,036,892, 6,284,899, 6,410,751, 5,650,525, 5,731,445,5,877,333, 5,929,254, 6,218,135, 6,228,653, 5,013,827, 5,068,339,5,652,345, 5,770,743, 5,132,204, 5,248,618, 5,603,868, 5,712,106,6,107,036, 4,952,707, 5,089,630, 5,112,960, 5,220,005, 5,326,882,5,330,900, 5,538,847, 5,543,295, 5,582,980, 5,591,591, 5,625,077,5,679,802, 5,707,559, 5,773,628, 5,783,387, 5,831,102, 5,840,919,5,843,681, 5,851,771, 5,869,699, 5,869,705, 5,871,938, 5,981,768,6,022,964, 6,063,574, 6,132,956, 6,133,459, 6,140,495, 6,355,441 and6,461,876. The boronic acid and boronate ester analogs of all of thesedioxetanes are considered to fall within the scope of the presentinvention and are expressly included as part of the disclosure of theinvention.

Chemiluminescence dan also be produced from the above signallingcompounds by reaction with a source of hydrogen peroxide followed byreaction of the hydroxy-substituted dioxetane in an organic solvent witha strong base such as hydroxide ion or fluoride ion. Polar aproticsolvents such as DMSO, DMF and acetonitrile are preferred for producinghighest intensity light.

Use of the above triggerable dioxetane signalling compounds of thepresent invention results in formation of a detectable product that canalso be detected on the basis of the change in molecular mass and by ¹Hor ¹³C NMR as described above. Moreover it is recognized that thechemiluminescent reaction of the triggerable dioxetane signallingcompounds results in a further fragmentation of the product in theprocess of producing chemiluminescence. It is recognized that thefragmentation or cleavage products can also be detected and/orquantified by molecular mass and by ¹H or ¹³C NMR as described above.Other reaction products described below that are detectable by achemiluminescent reaction also form subsequent products as the result ofa fragmentation reaction or an oxidative dimerization process. Thesefurther products have unique molecular mass and NMR properties which canserve as the basis of detection.

Substances that are useful as chemiluminescence enhancers are thosealready known in the art of chemiluminescence. Included among these arequaternary onium salts alone or in combination with anionic surfactantssuch as alkyl sulfate salts and alkyl sulfonate salts. Quaternary oniumsalts include quaternary ammonium and phosphonium salts such ascetyltrimethylammonium bromide, dicationic surfactants as described inU.S. Pat. No. 5,451,437, polymeric phosphonium salts as described inU.S. Pat. No. 5,393,469, polymeric ammonium salts as described in U.S.Pat. No. 5,112,960, polymeric mixed phosphonium and ammonium salts andmixtures of polymeric ammonium salts and additives as described in U.S.Pat. No. 5,547,836.

A representative procedure for the synthesis of a boronicacid-substituted dioxetane useful as a chemiluminescent signallingcompound is depicted below.

Additional chemiluminescent signalling compounds of the invention havethe formulas below

wherein Z is selected from O, S and NR⁸, wherein R⁸ is H or Si(R⁹)₃, R⁹is C₁-C₆ alkyl or phenyl, and X represents one or two halogensubstituents, preferably iodine, bromine or chlorine atoms. Reaction ofthe above signalling compounds with hydrogen peroxide replaces theboronic acid (or ester) substituent with a hydroxy group.Hydroxy-substituted indole compounds are described in e.g. U.S. Pat. No.5,589,238 as undergoing a spontaneous chemiluminescent reaction withambient oxygen.

The above indolyl, benzofuranyl and benzothiophenyl boronic acidderivatives can also be used in embodiments where color is measuredsince the indigo-like dimerized products are highly colored. Moreover,the aforementioned U.S. Pat. No. 5,589,238 as well as European PatentSpecification EP 0476930 B1 describe that this reaction also producesadditional hydrogen peroxide, presumably through reduction of oxygen.Use of an indolyl, benzofuranyl or benzothiophenyl boronic acidsignalling compound of the present invention will allow detection withgreater sensitivity since the hydrogen peroxide will be recycled in thereaction. Stated another way, each molecule of hydrogen peroxide iscapable of converting many molecules of signalling compound todetectable product.

Other chemiluminescent signalling compounds of the invention have theformula below

wherein LG is a leaving group and R¹⁰ and R¹¹ are hydrogen, C₁-C₄ alkylor are combined as an alkylene ring. Exemplary signalling compoundsinclude the carboxylic acid, ester and thioester derivatives.

In the structure above, R is a substituted of unsubstituted alkyl oraryl group, and AMP designates adenosine monophosphate. Reaction of theboronic acid or ester moiety with hydrogen peroxide will produce themolecule known as firefly luciferin. This compound is known to reactwith the firefly luciferase enzyme to produce bioluminescence. It isalso known to produce chemiluminescence upon treatment with strong baseby an oxidative process involving molecular oxygen.

Embodiments in which the leaving group is the AMP ester and theluciferase enzyme is used constitute a use of the present invention in abioluminescent method to detect a source of hydrogen peroxide. Such amethod comprises

a) reacting a signalling compound with a source of hydrogen peroxide toproduce a detectable product capable of undergoing a bioluminescentreaction;

b) reacting the detectable product with an enzyme and any necessaryco-factors for the enzyme to produce bioluminescence; and

c) detecting the bioluminescence.

The reaction can be conducted in different experimental modes. In onemode the carboxylic acid precursor can be reacted with peroxide in afirst step to replace the boronic acid or ester with the hydroxyl groupto produce the luciferin. The luciferin thus formed is then subjected tothe art-known conditions for eliciting bioluminescence, reaction withfirefly luciferase, Mg⁺² and ATP in a buffer. Since these two steps havediffering pH optima, each step can be conducted at its optimum pH orthey can be conducted at a single pH conducive to both reactions. Inanother mode of reaction the peroxide reaction is conducted concurrentlywith the luciferase/ATP reaction. reagents specifically identified forthis purpose in U.S. Pat. Nos. 5,618,682, 5,650,289 and 5,814,471.

Another group of signalling compounds capable of being detected bychemiluminescence have the formula:

wherein R⁵ and R⁶ are as described above. Reaction of the compound abovewith a source of hydrogen peroxide converts the boronic acid or estercompound into the known hydroxyaryl hydrazide compound. The latter areknown to undergo chemiluminescent reaction in aprotic solvent byreaction with strong base or in aqueous alkaline solution withadditional peroxide and optionally with a transition metal catalyst or aperoxidase enzyme.

Another group of signalling compounds comprise those boronic acid orboronate ester signalling compounds which are converted to a fluorescentphenolic product Sig-OH through reaction with hydrogen peroxide. Amongthe signalling compounds of the present invention which are converted tofluorescent products are substituted and unsubstitutednaphthaleneboronic acids and esters,

as well as the anthracene, phenanthrene and pyrene analogs, compounds ofthe formula which produce a coumarin or umbelliferone product,

benzothiazole boronic acids and esters of the formula

wherein Z is C—C double or triple bond or aromatic ring and n is 1 or 2,R⁹ is a cyano, imine or carbonyl group, and compounds which generateother fluorescers including resorufin and fluorescein and having thestructures below.

It should be recognized that the signalling compounds described abovewhich produce a chemiluminescent product also can be detected byfluorescence. This situation arises because the emitter in achemiluminescent reaction is, in nearly all cases, also fluorescent.

The above-mentioned signalling compounds which are converted to afluorescent phenolic product Sig-OH are useful in a method for detectinga source of hydrogen peroxide comprising:

a) reacting a signalling compound with a source of hydrogen peroxide toproduce a detectable product Sig-OH capable of detection byfluorescence;

b) irradiating the detectable product with light of a first wavelength;and

c) detecting light emitted as fluorescence from the detectable productat a second wavelength different from the first wavelength.

Another group of signalling compounds comprise those boronic acid orboronate ester signalling compounds which are converted to a coloredphenolic product Sig-OH through reaction with hydrogen peroxide. Amongthe signalling compounds of the present invention which are converted tocolored products include, without limitation, the exemplary structuresdepicted below.

Numerous other colored compounds containing a phenol moiety are known inthe art of colorimetric assays. Signalling compounds based on thesestructures but containing a boronic acid or boronate ester moiety inplace of the hydroxyl group are explicitly considered to be within thescope of the invention.

The above-mentioned signalling compounds which are converted to acolored phenolic product Sig-OH are useful in a method for detecting asource of hydrogen peroxide comprising:

a) reacting a signalling compound with a source of hydrogen peroxide toproduce a detectable product Sig-OH capable of detection by its color;and

b) detecting the formation of the detectable product by the formation orchange of color at a suitable wavelength or range of wavelengths.

Boronic acid and boronate ester compounds useful as signalling compoundsas described herein are generally prepared by reaction of a boronatingagent with an aryl halide or aryl triflate and a metal catalyst.

The metal catalyst is preferably a palladium compound used in thepresence of a phosphorus compound capable of acting as a ligand onpalladium. Representative palladium catalysts useful for effectingcarbon-boron bond formation are well known in the art of syntheticorganic chemistry and include divalent compounds PdL₂ with labileligands L selected from carboxylate esters, halogens and ketones andinclude palladium acetate, palladium chloride, palladiumbis(dibenzylideneacetone) Pd(dba)₂ and Pd₂ (dba)₃.

Phosphine ligands include PPh₃, PMe₃, PEt₃, Pt—Bu₃, Pt—Bu₂Me, Pt—Bu₂Et,P(cyclohexyl)₃, BINAP and mixed alkylarylphosphines such as DPPE, DPPF,DPPB and DPPP. Bases include KHPO₄, K₂CO₃, Na₂CO₃, CsCO₃, CsF, Et₃N andalkoxide salts such as sodium t-butoxide. Solvents useful in this stepinclude toluene, benzene, THF, DME, diglyme and alcohol solventsincluding t-butanol and t-amyl alcohol.

Commonly used boronating agents include trialkyl borates such astrimethylborate, triethlborate and triisopropyl-borate, diboroncompounds including bis(pinacolato)diboron,bis(neopentylglycolato)diboron.

The aromatic component is generally a bromide, iodide or triflatederivative of an aromatic hydrocarbon such as benzene, naphthalene,anthracene or pyrene or an aromatic heterocycle such as pyridine,quinoline, acridine, pyrrole, furan, benzofuran, thiophene,benzothiophene, oxazole, benzoxazole, thiazole, benzothiazole, xanthene,thioxanthene and phenothiazine any of which can be further substitutedor unsubstituted.

Other methods of synthesizing boronic acids are known. Reaction of arylbromide compounds with n-BuLi in THF at −78° C. produces an aryllithiumcompound which is reacted in situ with trimethyl borate or othertrialkyl borates to produce the arylboronate ester. Hydrolysis to thearylboronic acid normally ensues during the reaction workup whentrimethyl borate is employed.

Likewise Grignard reagents can be utilized in place of the aryllithiumintermediates mentioned above in a method of synthesizing arylboronicacids and their esters. Reaction of the aryl Grignard reagent with atrialkyl borate in ether solvent produces the arylboronate ester.

Arylboronic acids and esters can also be prepared from an aromatic ringcompound in a process using mercury-containing intermediates.Organomercury derivatives are converted to arylboronic acids (Q. Zheng,et al., Heterocycles, 37, 1761-72 (1994); N. Garg, et al., J. Am. Chem.Soc., 124, 13179 (2002)). For example, reaction of an indole compoundwith Hg(OAc)₂ produced the organomercurial Ar—Hg(OAc). Reaction of thelatter with borane (BH₃-THF) followed by hydrolysis produced anindole-3-boronic acid.

Arylboronate esters can also be prepared from arenes according to themethods disclosed in Ishiyama, et al., J. Am. Chem. Soc., 124, 390-1(2002). Reaction of an arene with an iridium catalyst with a bipyridylor phenanthroline ligand and a dialkylborane or diboron compound effectsdirect borylation of the aromatic ring of the arene.

Reactions of signalling compounds of the present invention with peroxideare carried out in solution such as an organic solvent or an aqueousbuffer or mixtures thereof. The reaction solution can be in contact withthe surface of a solid support such as a bead, tube, membrane ormicrowell plate. Reactions involving the use of enzymes are convenientlyperformed in a buffer. Suitable buffers include any of the commonly usedbuffers capable of maintaining a pH in the range of about 6 to about 10for example, phosphate, borate, carbonate,tris(hydroxymethylamino)methane (“tris”), glycine, tricine,2-amino-2-methyl-1-propanol (“221”), diethanolamine and the like. Thepreferred method of practicing the invention in this regard isdetermined by the intended use.

The amount of time used for performing the reaction of the signallingcompound with the source of hydrogen peroxide can vary over a widerange. Under conditions of alkaline solution reaction can be rapid,proceeding to completion in minutes. Under conditions of enzymaticgeneration of peroxide reaction times of hours can be used. Longerreaction times are not harmful even when the reaction is completedquickly. Conversely, short reaction times can be used even when it wouldnot permit consumption of all of the peroxide.

Embodiments involving fluorescent or chemiluminescent products requirethe detection of light emission. Light emitted by the present method canbe detected by any suitable known means such as a luminometer, x-rayfilm, high speed photographic film, a CCD camera, a scintillationcounter, a chemical actinometer or visually. Each detection means has adifferent spectral sensitivity. The human eye is optimally sensitive togreen light, CCD cameras display maximum sensitivity to red light, x-rayfilms with maximum response to either UV to blue light or green lightare available. Choice of the detection device will be governed by theapplication and considerations of cost, convenience, and whethercreation of a permanent record is required.

Signalling compounds of the present invention which produce light bymeans of fluorescence, chemiluminescence or bioluminescence typicallyemit light over a 100-200 nm wide band of emission, which exhibits amaximum intensity at wavelengths in the near ultraviolet to the visibleregion of the electromagnetic spectrum. Typical wavelengths of maximumintensity λ_(max) in the range of 350-750 nm. It is contemplated thatsignalling compounds bearing a covalently linked fluorophore couldundergo intramolecular energy transfer resulting in emission at longerwavelengths from the excited state of the fluorophore.

In a further embodiment, luminescent energy acceptors can be employed toshift the maximum emission to longer wavelengths (red-shifting) and/orto increase the quantity of luminescence emitted. Various techniques forred-shifting emission are known in the art of chemiluminescent reactionsand assays. Covalently linked fluorophores are one example. Fluorescerscan alternatively be added to the reaction solution as separate species.Fluorescers can be linked to a polymer or associated with a micelle orpolymer in order to bring the fluorescer in close contact to thecompound. Suitable energy transfer agents have an excited state at anenergy level which overlaps that of the excited reaction product topermit the transfer of excitation energy and a fluorescent excited statewhich may or may not be the same as the excited state which overlapsthat of the donor. Energy transfer agents useful for effectingsinglet-singlet energy transfer are well known in the art offluorescence. Energy transfer agents useful for effectingtriplet-singlet energy transfer are also known in the art and usuallypossess at least one metal atom or other heavy atoms such as bromine oriodine atoms. Typical examples are 9,10-dibromoanthracene (DBA),sulfonated derivatives of DBA and Ru(bpy)₃ ²⁺. Fluorescent energytransfer agents are evaluated empirically by comparing the intensity orwavelength of chemiluminescence produced in a reaction of a peroxide anda signalling compound as described above in the presence and absence ofthe agent.

Embodiments involving the formation of colored products require thedetection of color or the absorption of light. Detection can be by anysuitable known means. The simplest is visual observation of colordevelopment or color change. Photographic film or a digital camera canalso be employed for this purpose. Embodiments requiring quantitativemeasurement of color will best be performed by spectrophotometry. Choiceof the detection device will be governed by the application andconsiderations of cost, convenience, and whether creation of a permanentrecord is required.

The present invention includes the use of the methods and signallingcompounds for detecting hydrogen peroxide in an assay procedure.Reaction of a signalling compound of the invention with a source ofhydrogen peroxide produces the phenolic product which is detected by theappropriate means, i.e. color, absorbance, fluorescence or luminescenceas described above. The magnitude of the signal is then related to theamount of peroxide present. Quantitative relationships are readilyestablished by constructing calibration curves for any given signallingcompound and a set of peroxide standards of known concentration. Usesfor detection of hydrogen peroxide include the monitoring of biologicalor cellular processes, detection of antibodies which generate hydrogenperoxide, and the analysis of peroxide contamination in peroxide-formingsolvents. Several of the signalling compounds of the present inventionwhen dissolved in ether solvents such as p-dioxane rapidly give rise todetectable product, indicating the presence of peroxide contaminant.

In a further embodiment the present invention also relates to the use ofthese methods for detecting an enzyme which produces peroxide such as anoxidase enzyme or a dehydrogenase enzyme. It is well known that variousenzymes in the class of oxidase enzymes produce hydrogen peroxide as abyproduct of the reaction which oxidizes its substrate. Known oxidaseenzymes include galactose oxidase, glucose oxidase, cholesterol oxidase,amine oxidase, various amino acid oxidases, polyphenol oxidase, xanthineoxidase, uricase, alcohol dehydrogenase, lactate dehydrogenase, malatedehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, glyceroldehydrogenase, and glucose-6-phosphate dehydrogenase. In practice, theoxidase enzyme is reacted with a substrate for the oxidase enzyme toproduce hydrogen peroxide. Either concurrently or after a suitable timeperiod, the accumulated hydrogen peroxide is reacted with a signallingcompound of the invention to produce the phenolic product which isdetected by the appropriate means as described above. Further theoxidase or dehydrogenase enzyme can be present as a conjugate to abiological molecule or a member of a specific binding pair in an assayfor an analyte.

An important use of the present methods in biomedical and other analysisis for detecting the presence or amount of an analyte in an assayprocedure by a chemiluminescent, fluorescent, bioluminescent orcolor-forming reaction. One format comprises using an oxidase ordehydrogenase enzyme as a label on a specific binding pair member. Anexample is an enzyme-linked immunoassay, such as the so-calledenzyme-linked immunosorbent assay or ELISA. Such assays fall broadlyinto two categories. Competitive assays feature an immunological bindingof a specific antibody with the analyte and an analyte analog, e.g. adetectably labeled analyte molecule. Sandwich assays result by thesequential or simultaneous binding of two antibodies, one of which isdetectably labeled, with the analyte. The detectably labeled bindingpair so formed is assayed with the compounds and methods of the presentinvention. When the detectable label is the oxidase enzyme, it isdetected directly. When the detectable label is a member of anotherspecific binding pair, e.g. a hapten, a conjugate of its binding partnerwith an oxidase is reacted first and the oxidase then detected inaccordance with the present methods. Measurement can be performed withenzyme-labeled species in a solution or attached to a solid surface orsupport including beads, tubes, microwells, magnetic particles, teststrips, membranes and filters such as are in common use in the art.Other exemplary uses are the detection of proteins by the technique ofWestern blotting and nucleic acids by the use of enzyme-labeled nucleicacid probes including Southern blotting, northern blot analysis of RNA,and DNA sequencing.

Detection of the oxidase-labeled specific binding pair formed in theassay is conducted by supplying a substrate for the oxidase enzyme and,either concurrently or subsequently, supplying a signalling compound ofthe invention. Reaction of the oxidase with its substrate produceshydrogen peroxide. The hydrogen peroxide reacts with the signallingcompound to produce the phenolic product which is detected by theappropriate means as described above.

The method comprises the steps of contacting a sample suspected ofcontaining the analyte with a signalling compound of the presentinvention and a source of hydrogen peroxide, and detecting the phenolicproduct by means of chemiluminescence, fluorescence, bioluminescence orcolor in a qualitative method. If quantitation is desired, the amount ofphenolic product formed is related to the amount of the analyte. Therelationship between the detectable signal and amount of analyte can beeasily discerned by constructing a calibration curve with known amountsof the analyte. The signalling compound is typically used in aconcentration of about 10⁻⁸ M to about 10⁻² M, preferably between about10⁻⁶ M and about 10⁻³ M. Typical samples which can be analyzed by thepresent methods are body fluids such as blood, plasma, serum, urine,semen, saliva, sputum, cerebrospinal fluid and the like.

The present invention also includes embodiments wherein the signallingcompound contains a labelling group other than the boronic acid groupwhich permits labeling on a substance to be detected. The labeling groupcomprises a group having the formula -L-RG wherein L is a linker and RGis a reactive group.

The group L is a linking group which can be a bond or another divalentor polyvalent group, the group RG is a reactive group which enables thesignalling compound to be linked to another compound.

The linking group can be a bond, an atom, or a straight, or branchedchain of atoms some of which can be part of a ring structure. Thesubstituent usually contains from 1 to about 50 non-hydrogen atoms, moreusually from 1 to about 30 non-hydrogen atoms. Atoms comprising thechain are selected from C, O, N, S, P, Si, B, and Se atoms, preferablyfrom C, O, N, P and S atoms. Halogen atoms can be present assubstituents on the chain or ring. Typical functional groups comprisingthe linking substituent include alkylene, arylene, alkenylene, ether,peroxide, carbonyl as a ketone, ester, carbonate ester, thioester, oramide group, amine, amidine, carbamate, urea, imine, imide, imidate,carbodiimide, hydrazine, diazo, phosphodiester, phosphotriester,phosphonate ester, thioether, disulfide, sulfoxide, sulfone, sulfonateester, sulfate ester, and thiourea groups.

The reactive group RG is an atom or group whose presence facilitatesbonding to another molecule by covalent attachment or physical forces.In some embodiments, attachment of a signalling compound of the presentinvention to another compound will involve loss of one or more atomsfrom the reactive group, e.g. when the reactive group is a leaving groupsuch as a halogen atom or a tosylate group and the signalling compoundbonds to another compound by a nucleophilic displacement reaction. Inother embodiments, attachment of a signalling compound to anothercompound by covalent bond formation will involve reorganization of bondswithin the reactive group as occurs in an addition reaction such as aMichael addition or when the reactive group is an isocyanate orisothiocyanate group. In still other embodiments, attachment will notinvolve covalent bond formation, but rather physical forces in whichcase the reactive group remains unaltered. By physical forces is meantattractive forces such as hydrogen bonding, electrostatic or ionicattraction, hydrophobic attraction such as base stacking, and specificaffinity interactions such as biotin-streptavidin, antigen-antibody andnucleotide-nucleotide interactions.

The structure above bearing a biotin moiety as a reactive groupexemplifies a compound capable of specific binding interactions bynon-covalent means. Numerous specific linking groups and reactive groupsare listed in U.S. Pat. No. 6,126,870.

The present invention also includes embodiments wherein the signallingcompound is provided as a label on a substance to be detected. By thisis meant conjugates of a substance which is to be detected and at leastone signalling compound IV bearing a labeling substituent.

In order to more fully describe various aspects of the presentinvention, the following examples are presented which do not limit thescope of the invention in any way.

EXAMPLES

1. Synthesis of a Dioxetaneboronic Acid.

A mixture of 143.5 g of TiCl₃ and 17.64 g of LiAlH₄ was formed in 1 L ofcooled anhydrous THF under Ar by slow addition of the LiAlH₄ to thereaction system. A black mixture resulted. Triethylamine (130 mL) wasadded and the mixture heated to reflux. After 1 hour at reflux asolution of 20.62 g of methyl 3-bromobenzoate and 44.02 g ofadamantanone in 200 mL of anhydrous THF was added through a droppingfunel over 30 min. The reaction mixture was cooled and carefully pouredinto a solution of 6 L of water and 300 mL of triethylamine. The mixturewas extracted with 7×1 L of ethyl acetate and discarded. The ethylacetate extracts were combined, dried over Na₂ SO₄, filtered andevaporated to dryness leaving a white solid. The solid was washedseveral times with hexane and discarded. The hexane solutions werecombined, concentrated in volume and subjected to column chromatographywith 10-50% CH₂Cl₂/hexane. The alkene

was obtained in 67% yield. ¹H NMR (CDCl₃) δ 1.74-1.97 (m, 12H), 2.60 (brs, 1H), 3.24 (br s, 1H), 3.29 (s, 3H), 7.18-7.26 (m, 2H), 7.38-7.42 (m,1H), 7.47 (s, 1H).

A solution of 2.02 g of the bromoalkene and 1.68 mL of triisopropylborate in 10 mL of anhydrous THF and 40 mL of anhydrous toluene wasformed under Ar. The solution was cooled on dry ice and treated with2.91 mL of 2.5 M n-BuLi added over 30 min. The brown solution wasstirred another hour on dry ice, warmed to room temperature and leftover night. The colorless solution was quenched with 5 mL of water. Theboronic acid-substituted alkene of the formula

that precipitated was obtained in 98% yield. ¹H NMR (CDCl₃) δ 1.78-1.97(m, 12H), 2.67 (br s, 1H), 3.26 (br s, 1H), 3.30 (s, 3H), 7.02 (d, 1H),7.20 (t, 1H), 7.49-7.51 (m, 2H). Reaction of a sample with 10 μL of 30%H₂O₂ resulted in its conversion to the known hydroxyalkene.

A solution of the boronic acid-substituted alkene (1.02 g) in 25 mL ofmethanol containing methylene blue was cooled in an ice bath. Oxygen gaswas bubbled through the solution while it was irradiated with 1000 W Nalamp through a Kapton optical cutoff filter for 30 min. The solvent wasevaporated and the residue purified by column chromatography with 10-30%EtOAc/hexanes followed by acetone. The boronic acid-substituteddioxetane was obtained in 68% yield. ¹H NMR (CD₃OD) δ 1.01-1.06 (m, 1H),1.22-1.29 (m, 1H), 1.51-1.92 (m, 10H), 2.15 (br s, 1H), 3.04 (br s, 1H),3.22 (s, 3H), 7.49-8.20 (m, 4H).

2. Synthesis of Benzothiazoleboronic Acid Derivatives as SignallingCompounds for Fluorescent Detection.

a) Methyl 6-hydroxybenzothiazole-2-carboxylate was prepared byesterification of 6.0 g of the acid with HCl gas in 100 mL of methanol.Product (5.05 g, 79%) was isolated from the reaction by filtration, airdrying and washing with CH₂Cl₂ followed by hexanes. ¹H NMR (DMSO-d₆) δ3.94 (s, 3H), 7.13 (dd, 1H), 7.50 (d, 1H), 8.01 (d, 1H).

The hydroxy group of the ester was converted to the triflate ester byreacting 5.0 g with 13.0 g of N-phenyltrifluoromethanesulfonimide in 100mL of CHCl₃ and 12 mL of triethylamine at reflux for 1 h under Ar. Thereaction mixture was cooled, diluted to 250 mL with CHCl₃ and extractedsequentially with 20% aq. citric acid, water, and satd. aq. NaHCO₃. Theorganic layer was dried and evaporated. The product triflate (6.2 g,76%) was isolated by silica gel column chromatography with 25-100%CH₂Cl₂/hexanes. ¹H NMR (CDCl₃) δ 4.12 (s, 3H), 7.51 (dd, 1H), 7.95 (d,1H), 8.32 (d, 1H).

A reaction mixture containing 6.0 g of the triflate, 5.4 g ofbis(pinacolato)diboron, 0.40 g of Pd(OAc)₂, 0.93 g of triphenylphosphineand 8.1 g of CsF in 80 mL of anhydrous acetonitrile was refluxed underAr for 20 min. The mixture was cooled, diluted with acetonitrile andfiltered through Celite. The filter bed was washed with CH₂Cl₂ andEtOAc. The combined filtrates were adsorbed onto dry silica and thematerial subjected to column chromatography with 10-30% ethylacetate/hexanes. Product 2a was obtained (3.55 g, 60%) by evaporatingpooled fractions containing the product, washing the solid with hexaneand air drying. ¹H NMR (CDCl₃) δ 1.38 (s, 12H), 4.09 (s, 3H), 7.98 (d,1H), 8.22 (d, 1H), 8.47 (s, 1H).

b) Signalling compound 2a (3.05 g) was dissolved in 100 mL of methanol.Anhydrous NH₃ gas was bubbled through the solution causing a rise ontemperature. Bubbling was continued for 10 min. The reaction flask wascapped and the solution allowed to stand over night. The solvent wasthen evaporated to produce signalling compound 2b as a white solid 2.91g, 100%. ¹H NMR (CDCl₃) δ 1.38 (s, 12H), 5.86 (bs, 1H), 7.34 (bs, 1H),7.9 (d, 2H), 8.08 (d, 2H), 8.47 (s, 1H).

c) Signalling compound 2b was converted to nitrile 2c with POCl₃.Compound 2b (0.50 g) was added to 10 mL of POCl₃. The mixture wasstirred under a stream of Ar at 95° C. for 4 h. The mixture was cooledand evaporated to dryness. The residue was taken up in acetonitrile andpoured into ice-cold saturated NaHCO₃ solution. A tan solid formed andwas collected by filtration, washed with water and air dried. Compound2c, 0.40 g, 85% yield. ¹H NMR (CDCl₃) δ 1.38 (s, 12H), 8.04 (d, 1H),8.21 (d, 1H), 8.46 (s, 1H).

3. Synthesis of Coumarinboronic Ester Derivatives as SignallingCompounds for Fluorescent Detection.

7-Hydroxy-4-methylcoumarin was converted to the triflate ester byreacting 5.0 g with 15.2 g of N-phenyltrifluoromethanesulfonimide in 200mL of CHCl₃ and 20 mL of triethylamine at reflux for 5 h under Ar.During the reflux period an additional 3.0 g ofN-phenyltrifluoromethanesulfonimide was added. The reaction mixture wascooled over night and extracted with 2×200 mL of 10% citric acidfollowed by water wash. The organic layer was dried over Na₂SO₄ andevaporated. The clear colorless oil was crystallized from ether yieldingthe triflate ester, 8.72 g, 81%. ¹H NMR (CDCl₃) δ 2.47 (s, 3H), 6.37 (s,1H), 7.23-7.29 (m, 2H), 7.7 (d, 1H).

A reaction mixture containing 2.0 g of the triflate, 2.47 g ofbis(pinacolato)diboron, 164 mg of Pd(OAc)₂, 372 mg of triphenylphosphineand 4.6 mL of triethylamine in 30 mL of anhydrous acetonitrile wasrefluxed under Ar for 4 h. The mixture was cooled and filtered throughsilica gel with acetonitrile. The filtrate was adsorbed onto dry silicaand the material subjected to column chromatography with 0-50% ethylacetate/hexanes. Since the product was determined to be impure it wassubject to a second column using 50-100% CH₂Cl₂/hexanes. Product 3a wasobtained (326 mg, 17%). ¹H NMR (CDCl₃) δ 1.37 (s, 12H), 2.45 (s, 3H),6.33 (s, 1H), 7.58 (d, 1H), 7.70 (d, 1H), 7.74 (s, 1H).

A reaction mixture containing 251 mg of the triflate, 430.6 mg ofbis(neopentyl glycolato)diboron, 23 mg of Pd(Oac)₂, 49 mg oftriphenylphosphine, 0.60 mL of triethylamine and 15 mL of anhydrousacetonitrile was refluxed under Ar for 6 h and cooled over night. Themixture was filtered through silica gel with acetonitrile. The solventwas evaporated and the residue subjected to column chromatography with0-50% CH₂Cl₂/hexanes. Product 3b was obtained (79 mg, 36%) containing asmall amount of neopentyl glycol as an impurity. ¹H NMR (CDCl₃) δ 1.04(s, 6H), 3.80 (s, 4H), 6.31 (s, 1H), 7.57 (d, 1H), 7.69 (d, 1H), 7.74(s, 1H).

4. Synthesis of Pyreneboronic Acid Derivatives as Signalling Compoundsfor Fluorescent Detection.

A solution of 1.03 g of 2-bromopyrene in 30 mL of anh. THF was cooled to−78° C. under Ar. A solution of 1.50 mL of 2.5 M n-BuLi in hexanes wasadded dropwise causing a yellow precipitate to form. The reactionmixture maintained at −78° C. for another 30 min before dropwiseaddition of 0.42 mL of trimethylborate. After an additional 2 h at −78°C., the reaction mixture was warmed to room temperature. The reactionwas quenched with 5 mL of water. Addition of CH₂Cl₂ caused formation ofa precipitate of 381 mg of nearly pure 4a. The filtrate was evaporatedand the residue chromatographed with 20-30% EtOAc/hexanes to provide anadditional 76 mg of 4a. ¹H NMR (DMSO-d₆) δ 7.90 (d, 1H), 8.06-8.42 (m,7H), 9.00 (d, 1H).

A solution of 4.00 g of 2-bromopyrene, 3.97 g of bis(pinacolato)diboron,4.19 g of KOAc, and 0.29 g of Pd(dppf)Cl₂, in 30 mL of anh. DMSO was putunder Ar and heated at 85° C. for ca. 20 h. The mixture was cooled,poured into 200 mL of water and extracted with 3×100 mL of CH₂Cl₂. Thecombined CH₂Cl₂ extracts were washed with water, dried over Na₂SO₄ andevaporated. The residue was chromatographed on silica using 5-30%EtOAc/hexanes. Boronate ester 4b was obtained 3.61 g (78%) as a lightyellow solid. ¹H NMR (CDCl₃) δ 1.49 (s, 12H), 7.97-8.22 (m, 7H), 8.54(d, 1H), 9.07 (d, 1H).

Compound 4b was converted to compound 4a by reacting 1.0 g of 4b with1.96 g of NaIO₄ and 0.52 g of NH₄OAc in 100 mL of 50% aq. acetone withstirring for 5 days. The solution was filtered, the solids washed with100 mL of acetone and the filtrates combined and evaporated. Compound 4awas isolated from the residue by silica gel chromatography with 30-100%EtOAc/hexanes followed by 20% MeOH/EtOAc in 86% yield.

5. Synthesis of Phenanthreneboronic Acid Derivatives as SignallingCompounds for Fluorescent Detection.

A solution of 2.00 g of 9-bromophenanthrene, 2.17 g ofbis(pinacolato)diboron, 2.29 g of KOAc, and 0.19 g of Pd(dppf)Cl₂, in 10mL of anh. DMSO was put under Ar and heated at 85° C. over night. Themixture was cooled, poured into 100 mL of water causing a whiteprecipitate to form. The mixture was extracted with 2×100 mL of EtOAc.The combined EtOAc extracts were washed with water (emulsion!), driedover Na₂SO₄ and evaporated. The residue was chromatographed on silicausing 10% EtOAc/hexanes. Boronate ester 5b was obtained 2.27 g (96%) asa light yellow solid. ¹H NMR (CDCl₃) δ 1.46 (s, 12H), 7.55-7.70 (m, 4H),7.94 (d, 1H), 8.39 (s, 1H), 8.66-8.73 (m, 2H), 8.81-8.85 (m, 1H).

Compound 5b was converted to compound 5a by reacting 2.07 g with 4.37 gof NaIO₄ and 1.15 g of NH₄OAc in 100 mL of 50% aq. acetone with stirringfor 6 days. The solution was filtered, the solids washed with 50 mL ofacetone and the filtrates combined and evaporated. Compound 5a (1.06 g,70%) was isolated from the residue by silica gel chromatography with30-100% EtOAc/hexanes followed by 20% MeOH/EtOAc and then washing thesolid product in CHCl₃. ¹H NMR (DMSO-d₆) δ 7.64-7.74 (m, 4H), 8.12 (d,1H), 8.45-8.92 (m, 2H), 8.70 (s, 1H), 9.36 (d, 1H)

6. Synthesis of Anthraceneboronic Acid Derivatives as SignallingCompounds for Fluorescent Detection.

A solution of 2.00 g of 9-bromoanthracene, 2.17 g ofbis(pinacolato)diboron, 2.29 g of KOAc, and 0.19 g of Pd(dppf)Cl₂, in 10mL of anh. DMSO was put under Ar and heated at 85° C. for 24 h. Themixture was cooled, poured into 100 mL of water causing a whiteprecipitate to form. The mixture was extracted with 3×100 mL of EtOAc.The combined ELOAc extracts were washed with water (2×100 mL), driedover Na₂SO₄ and evaporated. The residue was chromatographed on silicausing 10-25% EtOAc/hexanes. Boronate ester 6 was obtained 1.29 g (54%)as a white solid. ¹H NMR (CDCl₃) δ 1.58 (s, 12H), 7.41-7.51 (m, 4H),7.99 (d, 2H), 8.44 (d, 2H), 8.48 (s, 1H).

7. Synthesis of Bis(benzothiazole)boronic Acid Derivatives as SignallingCompounds for Fluorescent Detection.

A solution of 2.0 of 6-bromo-2-cyanobenzothiazole, and 1.0 mL of2-aminothiophenol in 100 mL of methanol was stirred under Ar for severaldays. The white solid was collected by filtration and washedsequentially with methanol, 2-propanol and hexane. Air drying left 2.71g (93%) of 6-bromo-2,2′-bis(benzothiazolyl).

The bromide (0.50 g), 0.402 g of bis(pinacolato)diboron, 0.424 g ofKOAc, and 35.3 mg of Pd(dppf)Cl₂, in 10 mL of anh. DMSO was put under Arand heated at 85° C. over night. The mixture was cooled, poured into 200mL of water causing a brown precipitate to form. The solid was collectedby filtration and washed sequentially with water, 2-propanol and hexane.Air drying left 0.356 g (63%) of compound 7b. ¹H NMR (CDCl₃) δ 1.39 (s,12H), 7.47-7.59 (m, 2H), 7.98 (t, 2H), 8.13-8.18 (m, 2H), 8.47 (s, 1H).

The bromide (0.50 g), 0.358 g of bis(neopentylglycolato)diboron, 0.424 gof KOAc, and 35.3 mg of Pd(dppf)Cl₂, in 10 mL of anh. DMSO was put underAr and heated at 85° C. over night. The mixture was cooled and filteredand the solids washed with acetone. This solid was taken up in 125 mL ofCH₂Cl₂ and passed through a plug of Celite to remove residual Pd.Evaporation of solvent produced 375 mg of compound 7c (68%). ¹H NMR(CDCl₃) δ 1.06 (s, 6H), 3.83 (s, 4H), 7.46-7.59 (m, 2H), 7.96-8.01 (m,2H), 8.12-8.18 (m, 2H), 8.46 (s, 1H).

Attempted dissolution of 7c in D₂O for NMR analysis caused rapidhydrolysis to compound 7a. The filtrate from the initial reaction waspoured into 200 mL of water causing a brown precipitate to form. Thesolid was collected by filtration and washed sequentially with2-propanol and hexane to provide compound 7a. ¹H NMR (DMSO-d₆) δ7.57-7.68 (m, 2H), 8.02 (d, 1H), 8.14-8.28 (m, 3H), 8.34 (s, 1H), 8.59(s, 1H).

8. Synthesis of Benzothiazoleboronic Acid Derivative as SignallingCompound for Luminescent Detection.

A solution of 390 mg of compound 2c in 25 mL of methanol was spargedwith Ar. An Ar-sparged solution of 290 mg of D-cysteine hydrochloride in5 mL of water adjusted to pH 8 with NaHCO₃ was added by pipet. Anadditional 5 mL of water was added to the solution. Condensation of thenitrile and cysteine was immediate so the methanol was evaporated andthe remaining solution diluted to 100 mL with 20% conc. HCl. The whiteprecipitate was collected by filtration, washed with water and airdried. Compound 8 was obtained 381 mg, 91% yield. ¹H NMR (CDCl₃) δ3.68-3.84 (sextet, 2H), 5.46 (t, 1H), 7.99 (d, 1H), 8.12 (d, 1H), 8.33(s, 2H), 8.54 (s, 1H).9. Synthesis of an Indoleboronic Acid Signalling Compound.

3-Bromoindole is converted to the p-toluenesulfonamide derivative byreaction with p-toluenesulfonyl chloride and triethylamine.Alternatively, indole can be protected as the SEM derivative by reactionwith (Me₃SiOCH₂CH₂OCH₂Cl) SEMCl and NaH. The N-protected indole isbrominated at the 3-position by reaction with pyridinium tribromide orN-bromosuccinimide. The N-protected 3-bromoindole derivative isconverted to the 3-boronic acid derivative by metal-halogen exchangewith t-BuLi in deoxygenated anh. THF at −78° C. followed by reactionwith trimethyl or triisopropyl borate and aqueous hydrolysis. Finallythe protecting group is removed. Sulfonamides are hydrolyzed by reactionwith KOH in ethanol; SEM groups are removed with LiBF₄ in CH₃CN followedby aq. NaOH.

10. Chemiluminescent Detection of Hydrogen Peroxide with BoronicAcid-Substituted Dioxetane 1. The dioxetane signalling compound ofExample 1 was prepared in reagent compositions containingchemiluminescence enhancers and reacted with peroxide at 37° C. Thesolutions contained 1 mM dioxetane and 1 mg/mL of enhancer in 0.3 M trisbuffer, pH 9.35. Urea peroxide was added to achieve a finalconcentration of 10⁻⁵ M.

Enhancer t max Imax (RLU) Background I/B None 5 10.75 0.282 38 CTAB 11.549.2 0.81 61 Plus^(†) 25 1067 12.1 88 TB^(‡) 11.5 1001 5.9 1703TB/TO^(§) 15 >10000 123 >100 CTAB—cetyltrimethylammonium bromide

^(§)poly(vinylbenzyltributylphosphonium chloride) copolymer, Compound TBin U.S. Pat. No. 5,393,469^(‡)poly(vinylbenzyltributyl(trioctyl)phosphonium chloride) copolymer,in U.S. Pat. No. 5,393,46911. Sensitivity of Detection of Hydrogen Peroxide with a BoronicAcid-Substituted Dioxetane. A reagent composition (90 μL) containing 1mM dioxetane signalling compound of Example 1 in 0.3 M tris buffer, pH9.35 and 1 mg/mL of a poly(vinylbenzyltributylphosphonium chloride)copolymer, Compound TB in U.S. Pat. No. 5,393,469, was reacted withvarious concentrations of peroxide (10 μL) over the range 10 mM to 1 μM.Chemiluminescence intensity was measured after 4.5 min on triplicatesamples. FIG. 1 shows a plot of the corrected chemiluminescenceintensity as a function of the peroxide concentration in the reaction.The signal from the reaction solution with a final peroxideconcentration of 1 mM was ca. 3000 times that of the blank.15. Fluorescent Detection of Hydrogen Peroxide with 2-NaphthylboronicAcid. A solution of 1 mM 2-naphthylboronic acid was prepared in 0.2 M221 buffer, pH 9.6. A 0.1 M stock solution of urea peroxide was preparedin deionized water. Ten-fold serial dilutions of the peroxide solutionwere prepared down to 1×10⁻⁹ M. Reaction solutions containing 100 μL of2-naphthylboronic acid solution and 100 μL of each peroxide dilutionwere prepared in 1 cm cuvettes. Fluorescence excitation and emissionmaxima for the product were 380 nm and 465 nm, respectively.

Final [Peroxide] M I_(FL) (10 min) 5 × 10⁻⁴ 103.1 5 × 10⁻⁵ 15.85 5 ×10⁻⁶ 5.76 5 × 10⁻⁷ 4.74 Blank 4.6016. Fluorescent Detection of Glucose Oxidase with 2-NaphthylboronicAcid. Dilutions of glucose oxidase containing from 4.5×10⁻¹⁴ to1.5×10⁻¹⁷ moles of enzyme in 3 μL of water were placed in triplicatewhite microwells. A solution of glucose (50 μL of 0.1 M) in 10 mM trisbuffer, pH 7.0 was added to each well. The wells were incubated at 25°C. for 30 min. Then 50 μL portions of the reagent of Example 15 wereadded to each well. Fluorescence was measured after 15 min. FIG. 2depicts the linear response of fluorescence to glucose oxidase over therange of the assay.17. Fluorescent Detection of Glucose with 2-Naphthylboronic Acid.Dilutions of glucose containing between 5×10⁻⁸ and 5×10⁻¹¹ moles ofglucose in 3 μL of water were placed in triplicate white microwells.Then 100 μL portions of the reagent of Example 15 also containing 3×10⁻⁷M glucose oxidase were added to each well. Fluorescence was measuredafter 30 min. FIG. 3 depicts the linear response of fluorescence toglucose oxidase over the range of the assay.18. Fluorescent Detection of Hydrogen Peroxide with aBis(benzothiazolylboronate Ester. 50 μL of a 1 mM solution of thebis(benzothiazolyl)boronic acid ester 7b

in 0.2 M 2-amino-2-methyl-1-propanol buffer, pH 9.6 was treated withaqueous solutions containing hydrogen peroxide. Fluorescence excitationand emission spectra shown in FIG. 4 were measured before and afteraddition of 0.1 mM urea peroxide with a Jobin Yvon/SPEX Fluoroskanspectrofluorometer. Fluorescence excitation and emission maxima for theproduct were 419 nm and 571 nm, respectively.19. Fluorescent Detection of Hydrogen Peroxide with4-Methylcoumarin-7-boronic Acid. A 50 μL solution of 0.5 mM4-methylcoumarin-7-boronic acid pinacol ester in 0.3 M tris buffer, pH9.3 was prepared. Urea peroxide was added to achieve a concentration of3 mM. The grow-in of fluorescence at 440 nm is shown in FIG. 5.

Fluorescence excitation and emission maxima for the product were 360 nmand 440 nm, respectively.20. Fluorescent Detection of Urea Peroxide with Other FluorescentSignalling Compounds. Procedure: A 0.1 mM solution of each of thesignalling compounds listed in the table was prepared in 0.3 M trisbuffer, pH 9.35. A 3 mL portion of each solution was added to a 1 cmcuvette and the emission spectrum recorded. Urea peroxide was added toeach solution to achieve a concentration of 1 mM and the resultingsolutions allowed to react for 15 min. The emission spectrum wasrecorded at this point and again after 24 hours. In each case thefluorescence of the phenolic product reached maximum intensity in 15 minand remained constant at 24 hours.

Compound λex (nm) λem (nm) Intensity (RLU) 4a 335 480 1 × 10⁵ 4b 335 4801 × 10⁵ 5a 400 450 2 × 10⁶ 5b 400 450 2 × 10⁶The starting boronic acid or ester signalling compounds were negligiblyfluorescent under the conditions of measurement. The maximal emissionwavelengths shifted ca. 100 nm on conversion of the signalling compoundto the corresponding phenolic product.21. Colorimetric Detection of Hydrogen Peroxide with4-Nitrophenylboronic Acid. A 20 mM stock solution of4-nitrophenylboronic acid was prepared in ethanol and diluted 1:100 in0.3 M tris buffer, pH 9.35 to prepare a 0.2 mM working solution A. A 1.0M stock solution of urea peroxide was prepared in deionized water.Ten-fold serial dilutions were prepared down to 1×10⁻⁹ M from the stocksolution. Reaction solutions containing 3.0 mL of solution A and 10 μLof each peroxide dilution were prepared in 1 cm cuvettes and theabsorbance at 405 nm measured in each cuvette as a function of time.

Absorbance Final [Peroxide] M 10 min 20 min 60 min 24 hours 3.3 × 10⁻³0.183 0.500 1.393 3.57  3.3 × 10⁻⁴ 0.028 0.062 0.186 1.839 3.3 × 10⁻⁵0.011 0.013 0.028 0.249 3.3 × 10⁻⁶ 0.025 0.024 0.027 0.049 3.3 × 10⁻⁷0.013 0.012 0.013 0.01922. Bioluminescent Detection of Hydrogen Peroxide with BoronicAcid-Substituted Compound 8. Reaction of compound 8 with hydrogenperoxide produced D-luciferin. Reaction of the generated D-luciferinwith ATP, Mg+² salt and luciferase produced the characteristic greenishbioluminescence.23. Dual Chemiluminescent/Colorimetric Detection of Hydrogen Peroxide. Asolution is prepared containing the indoleboronic acid signallingcompound of example 9 (0.1 mM) in 0.1 M diethanolamine buffer, pH 10. A1.0 M stock solution of hydrogen peroxide is prepared in deionizedwater. Ten-fold serial dilutions are prepared down to 1×10⁻⁹ M from thestock solution. Reaction solutions containing 2 mL of indoleboronic acidsolution and 100 μL of each peroxide dilution or water for a blank wereprepared in 1 cm cuvettes. A 100 μL aliquot is transferred to aluminometer tube and chemiluminescence measured after 2 min. Absorbanceof the reaction solutions is measured at a suitable wavelength, e.g. 600nm.24. Synthesis of Additional Dioxetaneboronic Acids.

Dioxetanes 10a-b are prepared by a process analogous to the onedescribed in example 1. The known compounds 5-chloro-2-adamantanone andeither methyl 4-chloro-3-bromobenzoate (for 2a) or methyl3-bromobenzoate (for 2b) are coupled with the reagent prepared fromTiCl₃ and LiAlH₄. The bromoalkene is converted to the boronic acidalkene by reaction with B(Oi-Pr)₃ and n-BuLi in THF followed byhydrolysis. The boronic acid alkene is photooxygenated by irradiationwith a Na lamp under a stream of O₂ with methylene blue sensitizer toyield dioxetane 2a or 2b.

Dioxetane 11 is prepared by a process analogous to the one described inexample 1. The known diisopropyl ketone and methyl 3-bromobenzoate arecoupled with the reagent prepared from TiCl₃ and LiAlH₄. The bromoalkeneis converted to the boronic acid alkene by reaction with B(Oi-Pr)₃ andn-BuLi in THF followed by hydrolysis. The boronic acid alkene isphotooxygenated by irradiation with a Na lamp under a stream of O₂ withmethylene blue sensitizer to yield dioxetane 11.

Dioxetane 12 is prepared by a process analogous to the one described inexample 1. The known compound 3-bromo-4-chlorobenzoic acid is esterifiedin 2,2,2-trifluorethanol with acid catalysis to prepare thetrifluoroethyl ester. Methyl 3-bromobenzoate and 2,2,2-trifluorethyl3-bromo-4-chlorobenzoate are coupled with the reagent prepared fromTiCl₃ and LiAlH₄. The bromoalkene is converted to the boronic acidalkene by reaction with B(Oi-Pr)₃ and n-BuLi in THF followed byhydrolysis. The boronic acid alkene is photooxygenated by irradiationwith a Na lamp under a stream of O₂ with methylene blue sensitizer toyield dioxetane 12.

Dioxetane 13 is prepared by a process analogous to that disclosed in EP0779293A1 depicted below. Briefly, 3-bromobenzoic acid is esterifiedwith 2,2,4,4-tetramethyl-1,3-propanediol to produce the ester (i). Thealcohol function is oxidized with pyridinium chlorochromate (PCC) toform (ii). Reductive coupling of the ketone and ester groups withTiCl₃/LiAlH₄ produces the cyclic vinyl ether (iii). Conversion to theboronic acid is done with triisopropyl borate, followed by hydrolysis asdescribed above. The double bond is photooxygenated as above to producedioxetane 13.

Dioxetane 14 is prepared by a process analogous to the one described inexample 1. The known ketone tricyclo[7.3.2.0^(2,7)]tridec-2,7-ene-13-one(U.S. Pat. No. 6,461,876) and methyl 4-chloro-3-bromobenzoate arecoupled with the reagent prepared from TiCl₃ and LiAlH₄. The bromoalkeneis converted to the boronic acid alkene by reaction with B(Oi-Pr)₃ andn-BuLi in THF followed by hydrolysis. The boronic acid alkene isphotooxygenated by irradiation with a Na lamp under a stream of O₂ withmethylene blue sensitizer to yield dioxetane 14.25. Synthesis of Benzothiazoleboronic Acid Derivatives as SignallingCompounds for Luminescent Detection.

A solution of 1.0 g of compound 2c and 620 mg of DL-penicillamine wasprepared in 30 mL. THF. To this was added 2.0 mL of triethylamine wasadded followed by 3.0 mL of water. The solution was stirred for 1 hwhile being sparged with Ar. The solvent was evaporated, the residuetaken up in CH₂Cl₂ and the solution dried on MgSO₄. Evaporation of thesolvent yielded the triethylamine salt of 15a. The free acid wasliberated by taking the residue up in CH₂Cl₂, and washing the solutionwith 5% aq. citric acid followed by water, drying on MgSO₄ andevaporation of solvent. Compound 15a was obtained 1.34 mg, 92% yield. ¹HNMR (CDCl₃) δ 1.379 (s, 12H), 1.581 (s, 3H). 1.910 (s, 3H), 4.970 (s,1H), 7.957 (d, 1H), 8.140 (d, 1H), 8.432 (s, 1H).

Treatment of the boronate ester with aq. HCl as in example 8 producesthe boronic acid derivative 15b.

Compound 15a (1.0 g) and 0.44 g of carbonyl diimidazole (CDI) were addedto 30 mL of anh. CH₃CN. The reaction was stirred under Ar for 1 h beforeadding 0.5 mL of thiophenol. After stirring over night the yellowprecipitate was filtered, washed with CH₃CN and air dried producing 0.86g of 15c (70%). ¹H NMR (CDCl₃) δ 1.383 (s, 12H), 1.577 (s, 3H). 1.845(s, 3H), 4.939 (s, 1H), 7.451 (s, 5H), 7.962 (d, 1H), 8.152 (d, 1H),8.440 (s, 1H).

Attempted preparation of the phenyl ester of 15a by esterification withphenol and CDI produced instead

the oxidation product. This compound is useful as a fluorescentsignalling compound. ¹H NMR (CDCl₃) δ 1.383 (s, 12H), 2.482 (s, 3H),2.539 (s, 3H), 7.954 (d, 1H), 8.116 (d, 1H), 8.420 (s, 1H)

The foregoing description and examples are illustrative only and not tobe considered as restrictive. It is recognized that modifications of thespecific compounds and methods not specifically disclosed can be madewithout departing from the spirit and scope of the present invention.The scope of the invention is limited only by the appended claims.

1. A method for detecting the presence or absence of hydrogen peroxide,a salt of hydrogen peroxide or a complex of hydrogen peroxide in asample comprising: a) reacting the sample with a signalling compoundselected from the group consisting of a dioxetane compound of theformula

wherein A¹-A³ represent organic groups having from 1-20 carbon atoms andAr is an aromatic or heteroaromatic ring group, wherein A¹ and A² or A¹and A³ or A³ and Ar can be combined to form a ring, a compound of theformula

wherein Z is selected from O, S and NR⁸, wherein R⁸ is H or Si(R⁹)₃, R⁹is C₁-C₆ alkyl or phenyl, and X represents one or two iodine, bromine orchlorine atoms, a compound of the formula

wherein LG is a leaving group and R¹⁰ and R¹¹ are hydrogen, C₁-C₄ alkylor are combined as an alkylene ring, and a compound of the formula

wherein B is a boron atom, and each R is independently selected from thegroup consisting of hydrogen, alkyl and aryl groups and can be joinedtogether as a straight or branched alkylene chain forming a ring or asan aromatic ring; b) subjecting the reaction product of step (a) toconditions for a chemiluminescent reaction; and c) detectingchemiluminescence from the reaction of step (b), wherein the presence ofchemiluminescence indicates the presence of peroxide, wherein thesignalling compound itself does not undergo the chemiluminescentreaction.
 2. The method of claim 1 wherein the salt of hydrogen peroxideor a complex of hydrogen peroxide is selected from the group consistingof urea peroxide, perborate salts, percarbonate salts, percarboxylicacids and percarboxylic acid salts.
 3. The method of claim 2 wherein thehydrogen peroxide is produced in an enzymatic reaction.
 4. The method ofclaim 3 wherein the enzymatic reaction is a reaction of an oxidase ordehydrogenase enzyme with a substrate for the enzyme.
 5. The method ofclaim 4 wherein the oxidase or dehydrogenase enzyme can be present as aconjugate to a biological molecule or a member of a specific bindingpair.
 6. The method of claim 1 wherein the chemiluminescence signal ofstep (b) differs from that of the signalling compound by at least afactor of ten.
 7. The method of claim 1 wherein the chemiluminescencesignal of step (b) differs from that of the signalling compound by atleast a factor of
 100. 8. The method of claim 1 wherein thechemiluminescence signal of step (b) differs from that of the signallingcompound by at least a factor of
 1000. 9. The method of claim 1 furthercomprising, either before or concurrently with step b), reacting thedetectable product with a base to initiate the production ofchemiluminescence.
 10. The method of claim 1 wherein the signallingcompound is a dioxetane having the formula

wherein A¹-A³ represent organic groups having from 1-20 carbon atoms andAr is an aromatic or heteroaromatic ring group and wherein A¹-A³, Ar andR can be substituted with non-hydrogen atoms.
 11. The method of claim 10wherein A¹ and A² or A¹ and A³ or A³ and Ar are combined to form a ring.12. The method of claim 10 wherein the dioxetane has the formula:

wherein R¹ is an organic group having from 1-20 carbon atoms which canbe combined with R² or R³, R² is an aromatic or heteroaromatic ringgroup which can include additional substituents selected from halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, amino and alkylamino groups, R³ and R⁴ are independentlyselected from acyclic and cyclic organic groups containing from 3-20carbon atoms and which can be substituted with heteroatoms, and R⁵ andR⁶ are independently selected from hydrogen, alkyl and aryl groups andcan be joined together as a straight or branched alkylene chain forminga ring or as an aromatic ring.
 13. The method of claim 11 wherein R³ andR⁴ are combined together in a cyclic or polycyclic alkyl or a cyclic orpolycyclic alkenyl group which is spiro-fused to the dioxetane ring andcontains 6 to 20 carbon atoms and which can include additionalnon-hydrogen substituents.
 14. The method of claim 12 wherein R³ and R⁴are combined together to form an adamantyl group which can besubstituted with one or more substituent groups selected from halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, phenyl, substituted phenyl, amino and alkylamino groups. 15.The method of claim 12 wherein R³ and R⁴ are each branched alkyl orcycloalkyl groups having from 3-20 carbon atoms.
 16. The method of claim12 wherein the signalling compound has the formula:

wherein Y is a substituent group selected from hydrogen, halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, phenyl, substituted phenyl, amino and alkylamino groups. 17.The method of claim 12 wherein the dioxetane has the formula:


18. The method of claim 10 wherein the dioxetane has the formula:

wherein R¹ is an organic group having from 1-20 carbon atoms which canbe combined with R² or R³, R² is an aromatic or heteroaromatic ringgroup which can include additional substituents selected from halogens,alkyl, substituted alkyl, alkoxy, substituted alkoxy, carbonyl,carboxyl, amino and alkylamino groups, and R³ and R⁴ are independentlyselected from acyclic and cyclic organic groups containing from 3-20carbon atoms and which can be substituted with heteroatoms, and R⁵ andR⁶ are independently selected from hydrogen, alkyl and aryl groups andcan be joined together as a straight or branched alkylene chain forminga ring or as an aromatic ring.
 19. The method of claim 1 wherein thesignalling compound has the formula:

wherein Z is selected from O, S and NR⁸, wherein R⁸ is H or Si(R⁹)₃, R⁹is C₁-C₆ alkyl or phenyl, and X represents one or two iodine, bromine orchlorine atoms and the detectable product undergoes a chemiluminescentreaction with oxygen.
 20. The method of claim 1 wherein the signallingcompound has the formula:

wherein LG is a leaving group and R¹⁰ and R¹¹ are hydrogen, C₁-C₄ alkylor are combined as an alkylene ring.
 21. The method of claim 20 whereinthe leaving group is selected from OH, OR¹², SR¹² and O-AMP groups, R¹²is a substituted of unsubstituted alkyl or aryl group, and AMP isadenosine monophosphate.
 22. The method of claim 20 wherein the leavinggroup is selected from OH, OR¹² and SR¹², R¹² is a substituted ofunsubstituted alkyl or aryl group, and wherein step (b) comprisesreacting the reaction product of step (a) with a strong base andmolecular oxygen to produce chemiluminescence.
 23. The method of claim20 wherein the leaving group is the O-AMP group and AMP is adenosinemonophosphate and wherein step (b) comprises reacting the reactionproduct of step (a) with firefly luciferase enzyme and oxygen to producechemiluminescence.
 24. The method of claim 20 wherein the leaving groupis the OH group and wherein step (b) comprises reacting the reactionproduct of step (a) with ATP, Mg⁺², firefly luciferase enzyme and oxygento produce chemiluminescence.
 25. The method of claim 1 furthercomprising reacting the reaction product of step (a) in the presence ofat least one enhancer substance, wherein the enhancer is a quaternaryonium salt alone or in combination with an anionic surfactant whereinthe quaternary onium salt is selected from quaternary ammonium salts,quaternary phosphonium salts, dicationic surfactants, polymeric ammoniumsalts, polymeric phosphonium salts, polymeric mixed phosphonium andammonium salts and the anionic surfactant is selected from alkyl sulfatesalts and alkyl sulfonate salts.
 26. A method for detecting the presenceor absence of hydrogen peroxide, a salt of hydrogen peroxide or acomplex of hydrogen peroxide in a sample comprising: a) reacting thesample with a signalling compound selected from the group consisting of:

wherein B is a boron atom and wherein each R is independently selectedfrom hydrogen, alkyl and aryl groups and can be joined together as astraight or branched alkylene chain forming a ring or as an aromaticring; b) irradiating the reaction product of step (a) with light of afirst wavelength; and c) detecting the presence or absence of lightemitted as fluorescence at a second wavelength different from the firstwavelength, wherein the presence of fluorescent signal indicates thepresence of peroxide in the sample, and wherein the signalling compounditself does not emit fluorescence at the second wavelength or does soonly to a very weak degree.
 27. A method for detecting the presence orabsence of hydrogen peroxide, a salt of hydrogen peroxide or a complexof hydrogen peroxide in a sample comprising: a) reacting a signallingcompound selected from the group consisting of:

wherein B is a boron atom, and each R is independently selected fromhydrogen, alkyl and aryl groups and can be joined together as a straightor branched alkylene chain forming a ring or as an aromatic ring; and b)detecting the presence or absence of the formation or change of color ata suitable chosen wavelength or range of wavelengths wherein theformation or change of color indicates the presence of peroxide, andwherein the signalling compound itself is not colored at the chosenwavelength.
 28. The method of claim 1 wherein the reaction product ofstep (b) is detected in the presence of the starting signallingcompound.
 29. The method of claim 27 wherein the reaction product ofstep (a) is detected in the presence of the starting signallingcompound.
 30. The method of claim 26 wherein the reaction product ofstep (b) is detected in the presence of the starting signallingcompound.
 31. The method of claim 1 wherein the subjecting the reactionproduct of step (a) to conditions to cause it to undergo achemiluminescent reaction occurs spontaneously under the conditions ofthe reaction.
 32. The method of claim 1 wherein the subjecting thereaction product of step (a) to conditions to cause it to undergo achemiluminescent reaction comprises adding at least one additionalreagent.
 33. The method of claim 32 wherein the at least one additionalreagent is added after the reaction of the signaling compound with thesample.